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Solve 2cos^2x + cosx − 1 = 0 for x over the interval [0, 2 π ). a.π and π/3 b.π, π/3, and 5π/3 c.1 and 2π/3 d.1, 2π/3, and 4π/3 e.1, π/3, and 5π/3
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Solve 2cos^2x + cosx − 1 = 0 for x over the interval [0, 2 π ). a.π and π/3 b.π, π/3, and 5π/3 c.1 and 2π/3 d.1, 2π/3, and 4π/3 e.1, π/3, and 5π/3
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Jul 26, 2017
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Solve 2cos^2x + cosx − 1 = 0 for x over the interval [0, 2 π ).
a.π and π/3
b.π, π/3, and 5π/3
c.1 and 2π/3
d.1, 2π/3, and 4π/3
e.1, π/3, and 5π/3
Mathematics
high-school
Rupert Rawnsley
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Rupert Rawnsley
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Answer:
Option B is correct for plato
Explanation:
NFC Guy
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Jul 29, 2017
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NFC Guy
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Let cos x = a, then
2a^2 + a - 1 = 0,
solving the quadratic equation, we have:
a = 0.5 or -1.
i.e. cos x = 0.5 or cos x = -1
for cos x = 0.5,
x = pi/3, 2pi - pi/3 = pi/3, 5pi/3
for cos x = -1,
x = pi
therefore, x = pi, pi/3, 5pi/3
Answer: B
Selvakumar Arumugam
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Jul 30, 2017
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Selvakumar Arumugam
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